<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Title</title>
</head>
<body>

</body>
<script>
	// `typeof`运算符的返回类型为字符串 :
	// undefined、boolean、 string 、 number 、 object 、 function
	console.log(typeof undefined);// undefined
	console.log(typeof false);// boolean
	console.log(typeof "");// string
	console.log(typeof 1);// number
	console.log(typeof []);// object
	console.log(typeof {});// object
	console.log(typeof null);// object
	console.log(typeof function(){});// function
	console.log(typeof(1===1));// boolean
	console.log(typeof((function(){return 100})()));// number
</script>
</html>